Please help me with understanding classes/instances in python. I want to make a few buttons, and change color of the button, when it's clicked. I don't understand why on_touch_down changes the color of all the instances of the class, not the one that is touched. It's difficult for me to find answer because I don't know how to name it, I don't have much experience with objects. Please explain this. Thank you a million.
import kivy
from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.widget import Widget
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.textinput import TextInput
from kivy.graphics import Color, Ellipse
class MemoWidget(Button):
def on_touch_down(self, touch):
self.background_color=[100,100,1,1]
class MyApp(App):
def build(self):
root = BoxLayout(orientation='vertical',spacing=4)
m1 = MemoWidget()
m2 = MemoWidget()
m3 = MemoWidget()
root.add_widget(m1)
root.add_widget(m2)
root.add_widget(m3)
return root
if __name__ == '__main__':
MyApp().run()
You might think that on_touch_down only affects the widget you touch. But it affects all widgets of that class.
So what you might want, is on_press or on_release, to only affect the widget itself.
class MemoWidget(Button):
def on_release(self):
self.background_color=[100,100,1,1]
Related
I am trying to change to another screen by swiping the screen. I've tried carousel but it seems that it only works with images, so I've tried detecting a swipe motion and changing the screen after it has been detected.
main.py
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import Screen
from kivy.uix.button import ButtonBehavior
from kivy.uix.image import Image
from kivy.uix.label import Label
from kivy.uix.carousel import Carousel
from kivy.uix.widget import Widget
from kivy.uix.popup import Popup
class HomeScreen(Screen):
def on_touch_move(self, touch):
if touch.x < touch.ox: # this line checks if a left swipe has been detected
MainApp().change_screen(screen_name="swipedhikr_screen") # calls the method in the main app that changes the screen
class ImageButton(ButtonBehavior, Image):
pass
class LabelButton(ButtonBehavior, Label):
pass
class SettingsScreen(Screen):
pass
class SwipeDhikrScreen(Screen):
pass
#def quit_verification():
# pop = Popup(title="verification", content=Label(text= "Are you sure?"))
GUI = Builder.load_file("main.kv")
class MainApp(App):
def build(self):
return GUI
def change_screen(self, screen_name):
# get the screen manager from the kv file
screen_manager = self.root.ids["screen_manager"]
screen_manager.transition.direction = "up"
screen_manager.current = screen_name
def quit_app(self):
MainApp().stop()
MainApp().run()
I got an attribute error: "None type object has no attribute 'ids'"
MainApp().change_screen(screen_name="swipedhikr_screen")
This line creates a new instance of MainApp, which doesn't have any widgets and therefore naturally fails when you try to access them.
Use the existing instance of MainApp, i.e. the one that you're actually running, via MainApp.get_running_app().
Also you are not correct that Carousel works only with images.
I'm trying to use kivy for my project but I can't deal with it well..
I made a button, but I want that when I press him it will create another (new) button. Thanks a lot!
from kivy.app import App
from kivy.lang import builder
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.widget import Widget
from kivy.uix.button import Button
def createButton():
b = Button(pos=(0, 90), size_hint=(.2, .2), on_press=lambda a:ad())
return b
def ad():
"crate new button here!"
class NoobApp(App):
def build(self):
return createButton()
if __name__ == '__main__':
NoobApp().run()
In your ad() method add a line to create a Button and add it to the root of the app:
def ad():
print("crate new button here!")
App.get_running_app().root.add_widget(Button(text='hi'))
Note that this is adding a Button to a Button, (the root of the app is the original Button). Not a recommended approach. You should probably return some kind of Layout from your build() method instead.
Using this code:
from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.textinput import TextInput
class Main(App):
def build(self):
root = FloatLayout(size=(100, 100))
root.add_widget(TextInput(pos=(0, 0)))
root.add_widget(TextInput(pos=(50, 50)))
return root
if __name__ == '__main__':
Main().run()
I get two TextInputs, one on top of the other. When I click on the top TextInput (by clicking somewhere in the middle of the screen), the focus goes to the lower TextInput for some reason. In fact, the only way I can get focus on the top TextInput is by clicking entirely outside of the lower TextInput (by clicking right at the top of the screen). Why does this happen, and how can I circumvent this?
Your problem can be approached in two ways.Float layout honors the pos_hint and the size_hint properties of its children.So you need to set size_hint for textinput.
ie-
from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.textinput import TextInput
class Main(App):
def build(self):
root = FloatLayout(size=(100, 100))
root.add_widget(TextInput(pos=(0, 0),size_hint=(0.5,0.5)))
root.add_widget(TextInput(pos=(100, 100),size_hint=(0.5,0.5)))
return root
if __name__ == '__main__':
Main().run()
or use boxlayout instead of floatlayout
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.textinput import TextInput
class Main(App):
def build(self):
root = BoxLayout(size=(100, 100))
root.add_widget(TextInput(pos=(0, 0)))
root.add_widget(TextInput(pos=(50, 50)))
return root
if __name__ == '__main__':
Main().run()
I recently learnt about the Python framework kivy and started to follow the simple paint app tutorial. Now I want to save what was drawn as a .png file but instead of the colored dots it only exports the black background.
This is my code example:
import kivy
kivy.require("1.9.1")
from kivy.app import App
from kivy.uix.widget import Widget
from kivy.uix.button import Button
from kivy.graphics import Color, Ellipse, Line
class MyPaintWidget(Widget):
def on_touch_down(self,touch):
color=(0,0,1)
with self.canvas:
Color(*color)
d=30.
Ellipse(pos=(touch.x-d/2., touch.y-d/2.), size=(d,d))
class MyPaintApp(App):
def build(self):
parent=Widget()
self.painter=MyPaintWidget()
ssbtn=Button(text='Save')
ssbtn.bind(on_release=self.save_screenshot)
parent.add_widget(self.painter)
parent.add_widget(ssbtn)
return parent
def save_screenshot(self,obj):
self.painter.export_to_png("screenshot.png")
if __name__ == '__main__':
MyPaintApp().run()
What am I doing wrong? Thanks for your help.
You are missing one thing - Widget won't set its size and position automatically to whole Window size, but only to default ones i.e. pos = [0, 0] size = [100, 100] because Window != Layout and even adding it to something that doesn't inherit from a Layout won't make it better (Widget != Layout) which you can easily see if you look a that saved png (is too small).
self.painter=MyPaintWidget(size=[800,600])
will make the job for you if you plan to stay only on pc and only with the default Window size. If not, then use:
from kivy.core.window import Window
self.painter=MyPaintWidget(size=Window.size)
which seems to be more practical, yet you're still not there. An optimal solution would be using a Layout which does these things for you such as BoxLayout, GridLayout or some others.
And a perfect solution for you would be to use a StencilViewin a Layout, which when is placed won't take a screenshot of the whole canvas, but only the part you'd think it'll take i.e. the part sized as the Widget itself placed on its position.
Try drawing outside of the red box. Inspector will provide you with showing widgets in a color and other functions, so definitely try it as it was mentioned in the comments.
from kivy.app import App
from kivy.uix.widget import Widget
from kivy.uix.button import Button
from kivy.core.window import Window
from kivy.uix.stencilview import StencilView
from kivy.graphics import Color, Ellipse, Line, Rectangle
class MyPaintWidget(StencilView):
def on_touch_down(self,touch):
color=(0,0,1)
with self.canvas:
Color(*color)
d=30.
Ellipse(pos=(touch.x-d/2., touch.y-d/2.), size=(d,d))
class MyPaintApp(App):
def build(self):
parent=Widget()
self.painter=MyPaintWidget(size=[i/2.0 for i in Window.size])
with self.painter.canvas:
Color(1, 0, 0, 0.3)
Rectangle(pos=self.painter.pos, size=self.painter.size)
ssbtn=Button(text='Save')
ssbtn.bind(on_release=self.save_screenshot)
parent.add_widget(self.painter)
parent.add_widget(ssbtn)
return parent
def save_screenshot(self,obj):
self.painter.export_to_png("screenshot.png")
MyPaintApp().run()
I am trying to get the textinput widget to pass text into the callback function that makes a label with the text when called by the printbutton, should be fairly simple when you think about it. But I have a habit of not seeing the wood for the trees. Anyhoo, if anyone can figure this out then code it up :P
import kivy
kivy.require('1.5.1')
from kivy.app import App
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.uix.gridlayout import GridLayout
from kivy.uix.textinput import TextInput
class kivyentrywidget(GridLayout):
def __init__(self, **kwargs):
super(kivyentrywidget, self).__init__(**kwargs)
self.cols = 2
self.add_widget(Label(text='What do you want to print?'))
self.text_input = TextInput(multiline=False)
self.add_widget(self.text_input)
self.printbutton = Button(text='Print')
self.printbutton.bind(on_press=callback)
self.add_widget(self.printbutton)
def callback(self):
return Label(text=self.text_input.text)
class Firstapp(App):
def build(self):
return kivyentrywidget()
if __name__ == '__main__':
Firstapp().run()
def callback(self,evt=None): #not sure if kivy sends event info so added optional arg just in case
return self.add_widget(Label(text=self.text_input.text))
maybe ... not overly familiar with kivy but i think that would do it ..
also
self.printbutton.bind(on_press=self.callback)
should fix your other problem